JP4920311B2 - Oxidation autothermal reformer - Google Patents

Description

  The present invention relates to a reformer for producing a reformed gas containing hydrogen as a main component by a reforming reaction by bringing a mixture of hydrocarbon or aliphatic alcohol and steam into contact with a reforming catalyst, and more specifically, The present invention relates to a compact reforming apparatus in which oxidation heat in the apparatus can be used for a reforming reaction, and a reformer and a vaporizer for generating steam are integrated.

  Conventionally, a steam reforming type reforming system is known as a means for producing a reformed gas mainly composed of hydrogen by a reforming reaction by bringing a mixture of hydrocarbon or aliphatic alcohol and steam into contact with a catalyst. Yes. The reformer used in the steam reforming reforming system is provided with a combustion burner for heating at the center, and a reforming layer filled with a reforming catalyst is disposed so as to surround the combustion burner. It is common.

  On the other hand, as another method for producing a reformed gas mainly composed of hydrogen by a reforming reaction, an oxidizing gas is further accompanied with a mixture of hydrocarbon or aliphatic alcohol and water vapor, and a partial oxidation reaction layer is formed upstream. A self-heating type reforming method in which a steam reforming layer is provided downstream and the heat generated in the upstream partial oxidation reaction layer is used to supplement the heat of reforming reaction in the downstream steam reforming layer. Has been devised. This method has the advantage that the heat generated in the partial oxidation reaction layer supplements the reforming reaction heat in the steam reforming layer, eliminating the need for a combustion burner for heating, reducing heat loss, and reducing the size of the device. For example, techniques such as Japanese Patent Application Laid-Open No. 2001-192201 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2003-335504 (Patent Document 2) have been devised.

JP 2001-192201 A JP 2003-335504 A

  By the way, in order to produce a reformed gas mainly composed of hydrogen using a hydrocarbon or an aliphatic alcohol as a raw material, it is necessary to entrain the raw material with water vapor, and an apparatus for generating water vapor by some method is necessary. . In general, a steam generation means is provided separately from the reformer, and water is vaporized by the steam generation means to supply steam to the reformer. However, in this case, there is a problem that the number of devices constituting the entire reforming system increases and the system becomes large. In both the steam reforming reforming system and the autothermal reforming system, it is difficult to integrate the reformer and the steam generating vaporizer, and further miniaturization has been demanded. .

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-described problems of the prior art and provide a compact reformer in which a reformer and a vaporizer for generating steam are integrated.

  As a result of intensive studies to achieve the above object, the present inventors brought a reformed gas containing hydrogen as a main component through a reforming reaction by bringing a mixture of hydrocarbon or aliphatic alcohol and steam into contact with the reforming catalyst. In the manufacturing process, the modified layer and the oxidation exothermic layer have a cylindrical shape, and a triple tube structure in which the inner modified layer, the oxidation exothermic layer, and the outer modified layer are arranged in this order from the radially inner side. It has been found that by arranging a vaporizer for steam generation in a cylindrical space radially inside the inner reforming layer, the reformer and the vaporizer can be integrated to reduce the size of the entire system, and the present invention is completed. It came to.

That is, the oxidation autothermal reformer of the present invention is
In order to produce a reformed gas mainly composed of hydrogen by a reforming reaction by contacting a reformed catalyst at least partially with a mixture of hydrocarbon or aliphatic alcohol and steam with the reformed catalyst. A modified layer of
An oxidation heat generating layer that is at least partially filled with an oxidation catalyst and oxidizes a part of the reformed gas to generate heat;
A water vapor generating vaporizer for vaporizing water to generate water vapor;
The modified layer is disposed upstream of the oxidation heating layer;
The modified layer and the oxidation exothermic layer are cylindrical and have a triple tube structure in which the inner modified layer, the oxidation exothermic layer, and the outer modified layer are arranged in this order from the radially inner side,
At least part of the reforming catalyst filled in the inner reforming layer and the outer reforming layer contains Ru metal;
A steam generating vaporizer is disposed radially inside the inner reforming layer.

  Here, the oxidation autothermal reforming apparatus performs a reforming reaction that is endothermic and an oxidation reaction that is an exothermic reaction in the apparatus, and uses heat generated by the oxidation reaction as heat required for the reforming reaction. This is a type of reformer. In addition, although the oxidation autothermal reforming apparatus of this invention utilizes the heat | fever which generate | occur | produced by oxidation reaction for reforming reaction, it does not exclude the heating from the outside.

In the oxidation the self thermal reforming apparatus of the present invention, the inner at least a portion of the modified layer and the reforming catalyst packed in the outer reforming layer viewed contains a Ru metal, large liquid carbon atoms as reforming material Even if fuel is used, reforming can be performed with high reforming efficiency.

  In the oxidation autothermal reforming apparatus of the present invention, the steam generating vaporizer is preferably a boiler using hydrocarbon or aliphatic alcohol as fuel. In this case, since the hydrocarbon or the aliphatic alcohol can be used as a reforming raw material and as a fuel for a vaporizer for generating steam, the entire reforming system can be further downsized.

  According to the present invention, the modified layer and the oxidation heat generation layer have a cylindrical shape and have a triple tube structure in which the inner modification layer, the oxidation heat generation layer, and the outer modification layer are arranged in this order from the radially inner side, Furthermore, a vaporizer for steam generation is arranged in a cylindrical space radially inside the inner reforming layer, and a compact oxidation self-heat reforming apparatus in which the reformer and the vaporizer are integrated is provided. be able to.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic view of an embodiment of the oxidation autothermal reforming apparatus of the present invention, and FIG. 2 is a cross-sectional view taken along the line II-II in FIG. This oxidation autothermal reformer has a cylindrical shape as a whole, and each element is formed in an annular shape and arranged concentrically.

  The illustrated oxidation self-heating reformer 1 includes a reforming layer 2 and an oxidation heat generation layer 3, and the modification layer 2 is located upstream of the oxidation heat generation layer 3. The modified layer 2 and the oxidation heat generating layer 3 each have a cylindrical shape, and the modified layer 2 includes two layers of an inner modified layer 2A positioned on the radially inner side and an outer modified layer 2B positioned on the radially outer side. The oxidation exothermic layer 3 is disposed between the inner modified layer 2A and the outer modified layer 2B, and the inner modified layer 2A, the oxidation exothermic layer 3, and the outer modified layer 2B are arranged from the radially inner side. A triple tube structure arranged in the order of.

  The reforming layer 2 and the oxidation exothermic layer 3 are composed of an inner cylinder 4 and an outer cylinder 5 of the oxidation self-heating reformer 1, and two tubular partition walls 6 (radial direction) positioned between the inner cylinder 4 and the outer cylinder 5. The inner partition wall 6A is separated from the radially outer partition wall 6B), and the space between the inner cylinder 4 and the radially inner partition wall 6A forms the inner modified layer 2A, and the radially inner partition wall 6A is separated from the inner partition wall 6A. A space between the radially outer partition walls 6B forms the oxidation heat generating layer 3, and a space between the radially outer partition walls 6B and the outer cylinder 5 forms the outer modified layer 2B. As shown in detail in FIG. 2, the inner cylinder 4, the radially inner partition 6 </ b> A, the radially outer partition 6 </ b> B, and the outer cylinder 5 form an annular and concentric circular tube structure. The inner modified layer 2A, the oxidation heat generating layer 3, and the outer modified layer 2B, which are positioned between them, form a triple tube structure. Further, on the inner side in the radial direction of the inner cylinder 4, a vapor generating vaporizer 7 for vaporizing water to generate water vapor is disposed. As described above, in the oxidation self-heat reforming apparatus of the present invention, the reformer portion mainly composed of the reforming layer 2 and the oxidation heat generating layer 3 and the vapor generating vaporizer 7 are integrated. Therefore, it is possible to greatly reduce the size as compared with the conventional reforming system. In addition, the total thermal efficiency of the vaporizer and reformer is improved.

  The illustrated steam generator 7 includes a water supply pipe 8 for introducing water into the steam generator 7, a steam supply pipe 9 for supplying the generated steam, and the steam. A fuel supply pipe 10 for supplying fuel to the generator carburetor 7 and an exhaust gas passage 11 for discharging exhaust gas generated by the combustion of the fuel are connected. In the illustrated example, water is introduced into the vapor generating vaporizer 7 through the water supply pipe 8, and then converted into water vapor in the vapor generating vaporizer 7, and the generated vapor is supplied to the mixer 12 </ b> A through the vapor supply pipe 9. After being fed and mixed with the reforming raw material by the mixer 12A, it can be introduced into the oxidation autothermal reforming apparatus 1. The heat source of the vapor generating vaporizer 7 is not particularly limited, but in the oxidation self-heat reforming apparatus of the present invention, the vapor generating vaporizer 7 uses hydrocarbon or aliphatic alcohol as fuel. In this case, since the hydrocarbon or aliphatic alcohol can be used as a reforming raw material and also as a fuel for the vaporizer 7 for generating steam, the entire reforming system can be further reduced in size. It becomes possible to plan. In the illustrated example, the fuel combustion air supply pipe 13 is connected to the fuel supply pipe 10 via the mixer 12B. However, the combustion air supply system is not limited to this, For example, the combustion air supply pipe 13 may be directly connected to the vapor generating vaporizer 7.

  Further, the oxidation self-thermal reforming apparatus 1 shown in the drawing includes a raw material introduction pipe 14 for supplying raw materials to both the inner reforming layer 2A and the outer reforming layer 2B, and a reformed gas from the oxidation exothermic layer 3. A reformed gas discharge pipe 15 is connected to the lower part of the outer cylinder 5. Partition receivers 16A, 16B, and 16C are disposed above the position where the raw material introduction pipe 14 is connected and below the inner modified layer 2A, the oxidation heat generating layer 3, and the outer modified layer 2B. The partition receivers 16A, 16B, and 16C allow a mixture of a hydrocarbon or an aliphatic alcohol and water vapor and a reformed gas to pass through while preventing the catalyst or the like filled in each layer from falling. In addition, a partition wall 17 is disposed below the position where the raw material introduction pipe 14 is connected and above the position where the reformed gas discharge pipe 15 is connected. An opening 18 communicated with is provided. Furthermore, the oxidation autothermal reforming apparatus 1 in the illustrated example includes an oxidizing gas introduction pipe 19 that passes through the upper end portion of the outer cylinder 5 and reaches the oxidation heat generation layer 3, and is provided at the tip of the oxidizing gas introduction pipe 19. Is provided with a tubular ring 20 provided with a plurality of oxidizing gas outlets.

In the oxidation autothermal reforming apparatus of the present invention, the mixture of the steam and hydrocarbon or aliphatic alcohol generated in the steam generating vaporizer 7 as described above is converted into the inner reforming layer 2A and the outer reforming layer. A reformed gas mainly composed of hydrogen is produced by a reforming reaction by contacting with the reforming catalyst filled in 2B. Here, the mixing ratio of water vapor to the reforming raw material hydrocarbon or aliphatic alcohol can be selected as appropriate, but is usually in the range of H ₂ O / C (water / carbon) = 2-4. Also, the reforming raw material hydrocarbons and aliphatic alcohols are not particularly limited, and examples of the hydrocarbons include gases such as methane, ethane, propane, and butane, and liquid fuels such as light oil, gasoline, naphtha, and kerosene. On the other hand, as the aliphatic alcohol, methanol, ethanol, or the like can be used. Among these, the reformer of the present invention is suitable for reforming hydrocarbons having a large carbon number, that is, light oil, gasoline, naphtha, and kerosene, and is particularly suitable for reforming kerosene. Note that these hydrocarbons and aliphatic alcohols are also suitable as fuel for the steam generating vaporizer 7 as described above.

  In FIG. 1, the reforming raw material containing water vapor introduced from the raw material introduction pipe 14 into the raw material gas passage 21 passes through the partition receivers 16A and 16C, and the inner reforming layer 2A and the outer reforming layer 2B are up-flowed. The gas is reformed while flowing uniformly and becomes a reformed gas mainly composed of hydrogen. At this time, the heat required for the reforming is provided by the sensible heat generated by the oxidizing heat generated in the oxidation heat generating layer 3 being transmitted to the inner modified layer 2A and the outer modified layer 2B through the partition walls 6A and 6B. In the present invention, in addition to using the heat generated in the oxidation reaction for the reforming reaction, a part of the heat required for the reforming reaction can be supplied from the outside. It is possible to make the heat self-supporting by supplementing the heat necessary for the quality reaction with the heat generated in the oxidation exothermic layer (that is, the reaction proceeds only with the heat generated inside without supplying heat from the outside). preferable.

Here, in the present invention, as the reforming catalyst filled in the inner reforming layer 2A and the outer reforming layer 2B, catalysts conventionally used for reforming can be used, for example, alumina, silica, A support such as zirconia is used in which Ru, Ni, W, Co, Rh, and Pt are supported alone or in plural. At least a part of the reforming catalyst is a reforming catalyst containing Ru metal. A reforming catalyst containing Ru metal is excellent in reforming characteristics of a liquid fuel having a large number of carbon atoms and can improve its reforming efficiency. Specifically, reforming of light oil, gasoline, naphtha, and kerosene. It is particularly suitable for reforming kerosene. In general, although a catalyst supporting Ru has low oxidation resistance, in the present invention, the inner modified layer 2A and the outer modified layer 2B are arranged on the upstream side of the oxidation heat generating layer 3, and the inner modified layer is formed. Since no oxidizing gas is supplied to 2A and the outer reforming layer 2B, there is no need to consider the oxidation resistance of the catalyst, and a catalyst carrying Ru can be used. The reforming catalysts used for the inner reforming layer 2A and the outer reforming layer 2B may be the same or different.

The space velocity LHSV (Liquid Hourly Space Velocity) of the inner modified layer 2A and the outer modified layer 2B varies depending on the type of the reforming material, but is usually about LHSV = 0.1 to 1.0h ⁻¹ (based on the reforming material). Is preferred. The temperature of the inner reforming layer 2A and the outer reforming layer 2B varies depending on the type of raw material, operating conditions, etc. For example, when kerosene is used as the reforming raw material, it is usually maintained at about 400 ° C to 700 ° C. The

  The reforming raw material introduced into the oxidation autothermal reforming apparatus 1 as described above is partially or completely reformed in the inner reforming layer 2A and the outer reforming layer 2B, and is reformed mainly with hydrogen. It becomes a quality gas and enters the reformed gas flow path 22. The C1 conversion rate at this time is usually 90% or more, although it varies depending on the reforming raw material and operating conditions.

  Further, the reformed gas returns and enters the oxidation heat generating layer 3 in a down flow. The oxidizing heat generating layer 3 is connected with an oxidizing gas introduction pipe 19 as means for supplying an oxidizing gas, and an oxidizing gas outlet is provided at the tip of the oxidizing gas introduction pipe 19. A plurality of tubular rings 20 are installed. An oxidizing gas for oxidizing a part of the reformed gas to generate heat is ejected from the plurality of oxidizing gas ejection ports of the tubular ring 20 through the oxidizing gas introduction pipe 19. Here, as the kind of oxidizing gas to be used, pure oxygen can be used, but it is generally preferable to use air from the viewpoint of cost.

  In the oxidation exothermic layer 3, the oxidation reaction between hydrogen, methane, etc. in the reformed gas introduced into the oxidation exothermic layer 3 and the oxidizing gas in order to provide heat absorption in the inner reforming layer 2A and the outer reforming layer 2B. It is essential to perform (exothermic reaction), and the oxidation reaction is promoted by an oxidation catalyst. In the reformer of the present invention, since the inner modified layer 2A, the oxidation heat generating layer 3, and the outer modified layer 2B are arranged in this order from the inner side in the radial direction, the heat generated in the oxidation heat generating layer 3 is separated from the partition wall. It is quickly transmitted to the inner modified layer 2A and the outer modified layer 2B through 6A and 6B.

  First, the oxidation heat generating layer 3 can be filled with a mixture of an oxidation catalyst and a reforming catalyst. Here, the reforming catalyst used for the oxidation exothermic layer 3 further reforms methane and / or C2 + components (components having 2 or more carbon atoms) remaining in the reformed gas led to the oxidation exothermic layer 3. The endotherm for this reforming is directly covered by the heat generated by the oxidation reaction promoted by the mixed oxidation catalyst, creating a state in which reforming and oxidation proceed simultaneously. .

  Secondly, the oxidation heat generating layer 3 can be filled with a mixture of an oxidation catalyst and heat transfer particles. The oxidation exothermic layer 3 tends to have the highest temperature immediately below the oxidizing gas outlet, and the temperature decreases as it goes downstream. Therefore, by using partially heat transfer particles in the oxidation heat generation layer 3, the temperature difference between the upstream side and the downstream side of the oxidation heat generation layer 3 can be reduced. Here, the heat transfer particles transfer heat generated by the oxidation reaction to the entire oxidation exothermic layer 3, thereby upstream of the inner reforming layer 2 </ b> A and the outer reforming layer 2 </ b> B adjacent to the oxidation exothermic layer 3. On the side, the amount of heat transfer through the tubular partition walls 6A and 6B increases, and the temperature difference between the upstream and downstream sides of the inner modified layer 2A and the outer modified layer 2B can be reduced.

  Furthermore, thirdly, the oxidation heat generating layer 3 can be filled with a mixture of an oxidation catalyst, a reforming catalyst, and heat transfer particles. In this case, the oxidation heat generating layer 3 simultaneously exhibits the effects of the first case and the second case.

As the oxidation catalyst used for the oxidation heat generating layer 3, a catalyst supporting Pt, Pd or the like that hardly deteriorates at a high temperature is preferable. The addition amount of the oxidation catalyst is preferably not less than an amount necessary for supplementing the endotherm due to reforming and making the heat self-sustained and allowing the oxidizing gas to completely react. The GHSV of the oxidation catalyst is preferably in the range of 20,000 to 150,000 h- ¹ .

  As the reforming catalyst used for the oxidation exothermic layer 3, the reforming catalyst used for the reforming layer can be used. However, since the oxidation exothermic layer 3 is in an oxidizing atmosphere, Ni and Rh can be used alone or A catalyst supported in plural is suitable, and the catalyst can be prepared, for example, by supporting Ni, Rh alone or in a mixture on a support such as alumina, silica, zirconia or the like.

  In addition, the material of the heat transfer particles used for the oxidation heat generation layer 3 is not particularly defined, but a material having higher thermal conductivity is preferable, and silicon carbide particles are preferable.

  The installation position of the tubular ring 20 for ejecting the oxidizing gas is preferably a relatively upper portion in the oxidation heat generating layer 3, but is not particularly limited, and considering the gas flow and the direction of heat transfer, the inner modification A position higher than the quality layer 2A and the outer modified layer 2B is preferable. Further, the upper and lower sides of the tubular ring 20 for ejecting the oxidizing gas can be filled with the same mixture, but different ones can be filled.

The amount of oxidizing gas supplied from the oxidizing gas jetting tubular ring 20 to the oxidation heat generating layer 3 varies depending on the type of reforming raw material, but the oxygen / carbon ratio (O ₂ /C)=0.2 to About 0.6 is preferable. Thereby, the highest temperature part of the oxidation heat generating layer 3 becomes about 650-850 degreeC. Therefore, it is not necessary to use a particularly expensive material for the oxidation autothermal reforming apparatus of the present invention.

  The reformed gas partially oxidized and optionally reformed in the oxidation heat generating layer 3 passes through the partition receiver 16B, is led to the reformed gas flow path 23, and is discharged from the reformed gas discharge pipe 15. . After that, the discharged reformed gas usually contains carbon monoxide together with hydrogen and carbon dioxide. When the reformed gas is used as a power generation fuel for a solid oxide fuel cell (SOFC), carbon monoxide is used. Without being removed or converted, it is possible to supply the solid oxide fuel cell as it is, and it is not necessary to dispose the shift reaction layer on the downstream side of the oxidation heat generation layer 3.

  In the example shown in FIGS. 1 to 2, the raw material gas is introduced from the lower part of the reformer and the reformed gas is discharged from the lower part of the reformer. However, the reformer of the present invention is limited to this. For example, the raw material gas may be introduced from the upper part of the reformer and the reformed gas may be discharged from the upper part of the reformer.

It is a schematic side sectional view showing one embodiment of an oxidation autothermal reforming device of the present invention. It is sectional drawing which follows the II-II line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Oxidation autothermal reformer 2 Modified layer 2A Inner modified layer 2B Outer modified layer 3 Oxidation heat generating layer 4 Inner cylinder 5 Outer cylinder 6 Tubular partition 6A Radially inner partition 6B Radially outer partition 7 Steam generation Vaporizer 8 Water supply pipe 9 Steam supply pipe 10 Fuel supply pipe 11 Exhaust gas flow path 12A, 12B Mixer 13 Combustion air supply pipe 14 Raw material introduction pipe 15 Reformed gas discharge pipe 16A, 16B, 16C Partition receiver 17 Partition 18 Opening 19 Oxidizing gas introduction pipe 20 Tubular ring 21 Raw material gas flow path 22, 23 Reformed gas flow path

Claims (3)

In order to produce a reformed gas mainly composed of hydrogen by a reforming reaction by contacting a reformed catalyst at least partially with a mixture of hydrocarbon or aliphatic alcohol and steam with the reformed catalyst. A reforming layer, an oxidation catalyst that is at least partially filled with an oxidation catalyst, an oxidation exothermic layer for oxidizing part of the reformed gas to generate heat, and water vapor to generate water vapor An oxidation self-heating reformer in which the reforming layer is disposed on the upstream side of the oxidation heating layer,
The modified layer and the oxidation exothermic layer are cylindrical and have a triple tube structure in which the inner modified layer, the oxidation exothermic layer, and the outer modified layer are arranged in this order from the radially inner side,
At least part of the reforming catalyst filled in the inner reforming layer and the outer reforming layer contains Ru metal;
The oxidation autothermal reformer characterized in that the steam generating vaporizer is disposed radially inward of the inner reforming layer. The oxidation exothermic layer is filled with a mixture of an oxidation catalyst and a reforming catalyst, and the reforming catalyst used for the oxidation exothermic layer is a catalyst carrying Ni or Rh alone or in plural. 2. The oxidation autothermal reformer according to 1.   2. The oxidation autothermal reformer according to claim 1, wherein the steam generating vaporizer is a boiler using a hydrocarbon or an aliphatic alcohol as a fuel.

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